Vasodilators are medicines that help open blood vessels. The medicines affect the muscles in the walls of the arteries and veins. They prevent the muscles from tightening and the walls from narrowing.

As a result, blood flows more easily. The heart doesn't have to pump as hard. This lowers blood pressure.

The vasodilators that work directly on the blood vessel walls are:

• Hydralazine.
• Minoxidil.

Some other medicines used to treat high blood pressure also help open blood vessels. An example is calcium channel blockers.

Vasodilators are used to prevent, treat or improve symptoms in many conditions such as:

• High blood pressure.
• High blood pressure during pregnancy or childbirth.
• Heart failure.
• High blood pressure that affects the arteries in the lungs, called pulmonary hypertension.

Vasodilators are strong medicines. They generally are used only when other medicines haven't controlled blood pressure well enough.

Vasodilators may have side effects. Some side effects may need to be treated by taking other medicines.

Possible side effects of vasodilators include:

• Fast heartbeat.
• Fluttering, pounding or rapid heartbeat.
• Swelling due to fluid buildup in the body, called edema.
• Nausea.
• Vomiting.
• Headache.
• Excessive hair growth.
• Joint pain.
• Chest pain.

Talk to your healthcare team if you have any questions about the medicines you take.